The background description provided herein is for the purpose of generally presenting the context of the present invention. The subject matter discussed in the background of the invention section should not be assumed to be prior art merely as a result of its mention in the background of the invention section. Similarly, a problem mentioned in the background of the invention section or associated with the subject matter of the background of the invention section should not be assumed to have been previously recognized in the prior art. The subject matter in the background of the invention section merely represents different approaches, which in and of themselves may also be inventions. Work of the presently named inventors, to the extent it is described in the background of the invention section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present invention.
Fiber-optic communications begin with invention and applications of multimode optical fibers. Over the past decades, although singlemode optical fibers have become the main variety demanded in the fiber-optic market, the multimode optical fibers have never been replaced and have maintained a steady growth in market demands. And the reason is that many characteristics of the multimode optical fibers can just meet the use of optical signals, energy transmission, local area network (LAN) data transmission and optical devices. Moreover, the cost of a multimode fiber-optic communication system is far lower than that of a singlemode fiber-optic communication system, which is also one of the reasons why the multimode optical fibers are everlasting.
The 50 um multimode optical fibers are classified, according to the TIA/EIA-492AAA standard, into four types, OM1, OM2, OM3 and OM4. High-bandwidth multimode optical fibers (for example, OM3/OM4) are widely used in short-medium distance fiber-optic network systems due to low system cost. However, when the optical fibers are used indoor or in limited environments, the optical fibers endure a higher bending stress, which will lead to a higher bending loss. Therefore, a heretofore unaddressed need exists in the art to design and develop multimode optical fibers with bending-resistant character, so as to satisfy the need of indoor fiber-optic network construction and device miniaturization.
The existing related studies and patents only give the solutions of optimizing bending performance of the multimode optical fibers, such as Patent ZL201010029031.1 and Patent ZL201110029993.1, but do not give solution of optimizing DMD performance of the high-bandwidth multimode optical fibers (for example, OM3/OM4). In a transmission system of 10G or 100G, DMD is the most critical parameter that decides signal transmission. According to current technical requirements for developing the 10G or 100G transmission systems, an excellent DMD performance becomes more and more important, which decides the signal transmission stability, and directly represents the grade of the multimode optical fiber.
According to the TIA/EIA-492AAA standard, in a 10G network, the transmission distance of the OM3 optical fiber is no less than 300 m, and the transmission distance of the OM4 optical fiber is no less than 550 m; while in a 100G network, the transmission distance of the OM3 optical fiber is no less than 100 m, and the transmission distance of the OM4 optical fiber is no less than 150 m. Similarly, according to the TIA/EIA-492AAA standard, for a multimode optical fiber with the radius of 25 μm, at 850 nm, starting from the fiber core, the measured DMD value at the distance of 5 μm to 18 μm is defined as INNER MASK; and the DMD value at the distance of 0 to 25 μm is defined as OUTER MASK. The distance of 0 to 25 μm is further divided into 7 μm to 13 μm, 9 μm to 15 μm, 11 μm to 17 μm, and 13 μm to 19 μm, and the DMD values at the four distance sections are defined as INTERVAL MASK. Standards TIA/EIA-492AAAC and TIA/EIA-492AAAD respectively specify the DMD performance specification of the OM3 optical fiber and the OM4 optical fiber:
TABLE 1INNER MASK and OUTER MASK of the OM3optical fiber @ 850 nmDMD Inner MaskDMD Outer MaskDMD(Unit: ps/m)(Unit: ps/m)Templates(Radius 5 to 18 ìm)(Radius 0 to 23 ìm)1≦0.23≦0.702≦0.24≦0.603≦0.25≦0.504≦0.26≦0.405≦0.27≦0.356≦0.33≦0.33
TABLE 2INTERVAL MASK of the OM3 optical fiber @ 850 nmDMD Interval Mask (Unit: ps/m)Radius 7 to 13 μm≦0.25Radius 9 to 15 μm≦0.25Radius 11 to 17 μm≦0.25Radius 13 to 19 μm≦0.25
That is, the DMD values of the INNER MASK and the OUTER MASK of the OM3 optical fiber must satisfy any one of the six templates in Table 1, while according to Table 2, the INTERVAL MASKs of 7 μm to 13 μm, 9 μm to 15 μm, 11 μm to 17 μm, and 13 μm to 19 μm must be less than or equal to 0.25 ps/m.
TABLE 3INNER MASK and OUTER MASK ofthe OM4 optical fiber @850 nmDMD Inner MaskDMD Outer MaskDMD(Unit: ps/m)(Unit: ps/m)Templates(Radius 5 to 18 μm)(Radius 0 to 23 μm)1≦0.10≦0.302≦0.11≦0.173≦0.14≦0.14
TABLE 4INTERVAL MASK of the OM4 optical fiber @ 850 nmDMD Interval Mask (Unit: ps/m)Radius 7 to 13 ìm≦0.11Radius 9 to 15 ìm≦0.11Radius 11 to 17 ìm≦0.11Radius 13 to 19 ìm≦0.11
That is, the DMD values of the INNER MASK and the OUTER MASK of the OM4 optical fiber must satisfy any one of the three templates in Table 3, while according to Table 4, the INTERVAL MASKs of 7 μm to 13 μm, 9 μm to 15 μm, 11 μm to 17 μm, and 13 um to 19 um must be less than or equal to 0.11 ps/m.